Michigan State University Extension
Ornamental Plants plus Version 3.0 - 00001795
11/12/99
Sampling Soils
Once the landscape planting site has been selected, one of
the first priorities before planting is to test the soil
to determine the pH, the lime test index and fertilizer
needs. It is much easier and more desirable to adjust the
soil pH and nutrient status before planting. Ideally, the
initial soil samples should be taken and corrective
actions done a year or two prior to planting to allow time
for the needed soil amendments to produce their most
desirable effects.
A soil analysis is most valuable in established plantings
when used in conjunction with foliar analysis.
Because of the vast depth and breadth of the root systems
of woody plants, it is difficult to take a sample that
will represent the entire area where the root system
absorbs its nutrients. Therefore, a poor correlation may
exist between soil test and leaf analysis results for a
given nutrient. A foliar analysis does not indicate soil
pH, so both should be used to help diagnose suspected
mineral deficiencies. Soil tests should always accompany
foliar analysis of plants in tubs or planters, because the
pH of soil in containers can change rapidly.
Test soils in the landscape every three years and take
corrective action. Sample at least eight sites in an
average size lot, and combine and thoroughly mix them.
Dry the soil at room temperature and place a cupful in a
sample box available from county Cooperative Extension
Services offices.
For homeowners, areas near the house are likely to be
different from those a few feet away. Carefully evaluate
your lot to determine where subsoil has been exposed in
the process of grading around the building.
If the soil varies around the home, take a composite
sample from each distinct area. A composite sample made
up of samplings from two distinctly different areas does
not represent either area.
Taking the Sample
Sample a given area about the same time each nutrient
availability may vary with time of sampling.
From each predetermined area, regardless of size or use,
prepare a composite sample by taking no fewer than eight
samplings consisting of vertical columns or cores of soil
approximately 2 inches by 2 inches by 12 inches deep, or 2
inches in diameter and 12 inches in depth.
It has been found that eight well taken samplings or
soil cores per composite sample from a given area
regardless of size, will yield laboratory test results
that can be duplicated much more frequently than tests
based on samples made up of one or three samplings.
Avoid sampling unusual areas--those close to roads, the
foundation, previous locations of compost or manure piles,
fences, sidewalks or poorly drained areas--unless such
locations are sampled and packaged separately.
Subsoil samples taken at a depth of 18 to 24 inches,
especially with organic soils, will often aid in making
lime recommendations. Subsoil samples need not be
composites.
Break Clods--Mix Thoroughly
As you take the individual 1-cup samplings, place them in
a plastic pail until you have eight from the area
involved. Then mix the soil in the pail thoroughly with
your hands while holding the pail at an angle of 45
degrees and turning it. Do not use a metal pail if the
sample is to be tested for micronutrients.
If the soil is very wet at sampling time, it may be
necessary to partially air dry the sample to obtain an
adequately mixed sample. To prevent inaccurate test
results, avoid drying the sample with artificial heat or
in areas containing ammonia or other gases.
If the soil is very dry it may be necessary to crush the
cores to get a good mix. A clean wooden surface and a
rolling pin work well.
Preparing and Packaging the Sample
After the sample is thoroughly mixed, place a pint of the
soil in the container for sending to the testing
laboratory. You can buy special boxes provided by the MSU
Crop and Soil Sciences Department at your county Extension
office or directly from the MSU Crop and Soil Sciences
Department. Purchase the soil container pays for the soil
test.
If these are unavailable, any clean container of one-pint
capacity that be tightly closed should prove satisfactory.
Do not use rusty or otherwise contaminated containers,
such as metal cans--any foreign material may affect the
soil test.
Drying the soil samples prior to analysis may cause
changes in the availability of certain nutrients
particularly phosphorus. Do not force-dry the samples by
placing them on radiators or inside ovens before
submitting them to the laboratory.
Provide Complete Information
The more complete the information you provide, the better
the fertilizer recommendation.
Use a waxed pencil or pen to fill in the information
requested on the special soil container, or if you use
some other container, label the package with the owner's
name and address.
The following information should accompany the sample:
1. Previous land use.
2. Ornamental species, whether new or established
plantings.
3. What weed killers have been used?
4. Good or poor drainage?
5. Soil type, series or soil management group name,
if known.
6. Whether irrigation is to be used.
7. Special problems or conditions.
Information on the various soil tests available from the
MSU Soil Testing Laboratory is available from your county
Extension office.
The interpretation of the soil test results and the
fertilizer recommendations will accompany your soil test
report. Contact your garden center, retail nursery or
county Extension office for pertinent and timely
publications.
This information is for educational purposes only. References
to commercial products or trade names does not imply
endorsement by MSU Extension or bias against those not
mentioned. This information becomes public property upon
publication and may be printed verbatim with credit to MSU
Extension. Reprinting cannot be used to endorse or advertise
a commercial product or company.
This file was generated from data base ZZ on 01/19/00.
Data base ZZ was last revised on 11/12/99.
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